The invention relates to an infrared sensor having several rod-shaped thermocouples, which are described here as sensor rods, and to a thermal imaging camera having an infrared sensor of this type. The invention also relates to a method for producing a microstructure of thermoelectric sensor rods. Infrared sensors of the type mentioned and a corresponding production method is known from DE 10 2009 043 413 B3.
According to this document, an infrared sensor can be embodied as a three dimensional microstructure in which individual thermocouples are embodied in each case from two semiconductor rods that are arranged in parallel with one another and protrude in a self-supporting manner upwards from a base of a sensor. The two semiconductor rods are electrically connected to one another at their free ends so that together they form a double rod. Furthermore, the two semiconductor rods are embodied from materials that have a different Seebeck coefficient. It is therefore possible by way of conductor tracks in the sensor base to measure a so-called thermoelectric force between said two semiconductor rods, said force being in other words an electric voltage that occurs if there is a thermal difference between the free end of the double rod at which the two semiconductor rods are connected and its end at the sensor base. Each of the double rods can represent an image element (pixel—picture element) in an imaging surface of the infrared sensor.
In the case of infrared sensors similar to the type described here, endeavors are made to use in a best possible manner the infrared radiation that impinges on the infrared sensor so that it is possible to achieve an infrared image using just a small magnitude of radiation intensity.
For this purpose, the magnitude of the electric voltage that occurs at each of the thermocouples should be as large as possible in relation to the radiation intensity. Simultaneously, it should be possible to provide as many pixels per surface area unit as possible, in other words in the case of an infrared sensor as high as possible a pixel density, in order to obtain a high spatial resolution of the infrared images that are produced using the infrared sensor.